The CAS Registry Mumber 127510-61-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,7,5,1 and 0 respectively; the second part has 2 digits, 6 and 1 respectively. Calculate Digit Verification of CAS Registry Number 127510-61: (8*1)+(7*2)+(6*7)+(5*5)+(4*1)+(3*0)+(2*6)+(1*1)=106 106 % 10 = 6 So 127510-61-6 is a valid CAS Registry Number.